Rotary-to-linear transfer devices, also known as torque-to-thrust transfer devices, have a rotating input member and a linear moving output member. The roller members are disposed between the input member and the output member to permit the required relative rotation between these two units. The roller members are generally disposed in a group of three separated by 120 degrees and operate on an adjacent ramp, which is formed on the output member. The ramps and rollers are on the same radius. The rollers are dispersed at 120 degrees to provide for even distribution of force loads thus limiting the input motion to 120 degrees. This will limit the total linear travel especially when the ramp angle is chosen small enough to have a self-locking feature.